Cause of iron staining?


New member
May 24, 2019
Oswego, NY
Hi all!

First time poster, long time reader. I’ve owned my 24’ above ground pool for 7 years. I noticed discoloration on the liner after opening the pool this year and eventually discovered it was iron staining. I’m most of the way through a successful ascorbic acid/sequestrant treatment. My main concern is the cause of the staining (it was quite extensive). My initial thought was that is was due to a rusting bolt that was screwed into the filter where the pressure gauge use to be. Ive since replaced the bolt with a proper gauge. The bolt was so rusted the top broke off when I removed it. Anyways, I’m curious if a rusty bolt could cause such extensive staining. I have municipal water which I know could contain iron but is less likely than well water. I’m hoping it was the bolt and that once I remove the current iron, I’ll be good to go without always adding sequestrant. I have a culator on the way to help remove the metal and there was also sediment after AA treatment which I vacuumed to waste. Any thoughts? Before and after photos are attached to show staining.